Dubbed "Dynamic Weapon System" by Valve, Counter-Strike: Source's economy has been changed. For better or worse, the new system changes the prices of weapons based on their popularity by users. The latest changes/updates have now been released through Steam.

It has been well publicised as to how unhappy end users feel towards Valve's latest implimentation, but how much is that Deagle gonna cost you now? The function can be turned on/off via cvar on the server side.